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Merge pull request #344 from ethereum/hwwhww/chunk_size 

phase1: Adjust `CHUNK_SIZE`
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Hsiao-Wei Wang 2018-12-21 11:04:36 +08:00 committed by GitHub
parent eaab06f2dd e4e923fbba
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1 changed files with 4 additions and 4 deletions
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specs/core/1_shard-data-chains.md
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@ -18,7 +18,7 @@ Phase 1 depends upon all of the constants defined in [Phase 0](0_beacon-chain.md
| Constant | Value | Unit | Approximation | | Constant | Value | Unit | Approximation |
|------------------------|-----------------|-------|---------------| |------------------------|-----------------|-------|---------------|
| `CHUNK_SIZE` | 2**8 (= 256) | bytes | | | `SHARD_CHUNK_SIZE` | 2**5 (= 32) | bytes | |
| `SHARD_BLOCK_SIZE` | 2**14 (= 16384) | bytes | | | `SHARD_BLOCK_SIZE` | 2**14 (= 16384) | bytes | |
### Flags, domains, etc. ### Flags, domains, etc.
@ -78,8 +78,8 @@ To validate a block header on shard `shard_id`, compute as follows:
```python ```python
def merkle_root(block_body): def merkle_root(block_body):
assert len(block_body) == SHARD_BLOCK_SIZE assert len(block_body) == SHARD_BLOCK_SIZE
chunks = SHARD_BLOCK_SIZE // CHUNK_SIZE chunks = SHARD_BLOCK_SIZE // SHARD_CHUNK_SIZE
o = [0] * chunks + [block_body[i * CHUNK_SIZE: (i+1) * CHUNK_SIZE] for i in range(chunks)] o = [0] * chunks + [block_body[i * SHARD_CHUNK_SIZE: (i+1) * SHARD_CHUNK_SIZE] for i in range(chunks)]
for i in range(chunks-1, 0, -1): for i in range(chunks-1, 0, -1):
o[i] = hash(o[i*2] + o[i*2+1]) o[i] = hash(o[i*2] + o[i*2+1])
return o[1] return o[1]
@ -114,7 +114,7 @@ This outputs the root of a tree of the data roots, with the data roots all adjus
def mk_combined_data_root(depths, bodies): def mk_combined_data_root(depths, bodies):
data = b''.join(bodies) data = b''.join(bodies)
data += bytes([0] * (next_power_of_2(len(data)) - len(data)) data += bytes([0] * (next_power_of_2(len(data)) - len(data))
return compute_merkle_root([data[pos:pos+CHUNK_SIZE] for pos in range(0, len(data), CHUNK_SIZE)]) return compute_merkle_root([data[pos:pos+SHARD_CHUNK_SIZE] for pos in range(0, len(data), SHARD_CHUNK_SIZE)])
``` ```
Verify that the `shard_block_combined_data_root` is the output of these functions. Verify that the `shard_block_combined_data_root` is the output of these functions.